Mexico’s back-to-back earthquakes, explained by a seismologist

The quake that hit Mexico City on Tuesday comes less than two weeks after a magnitude 8.1 quake struck the country

The second major earthquake to strike Mexico in less than two weeks has caused catastrophic damage in the country’s capital. The magnitude 7.1 temblor cracked highways and collapsed buildings. So far, it has killed more than 200 people. Less than two weeks ago on September 7th, a magnitude 8.1 quake struck roughly 400 miles southeast from Tuesday’s.

This is why: The country sits at the boundary of three pieces of the Earth’s crust that fit together like a jigsaw puzzle — called tectonic plates (the Cocos plate, the North American plate, and the Pacific plate). Tuesday’s quake originated on a fault within the Cocos plate, which is on Mexico’s western edge. Mexico City is especially prone to severe damage because of the ground it sits on — an ancient lake-bed that quivers like jello, according to seismologists. When earthquake waves pass through it, it jiggles, magnifying the vibrations. At this point, a reasonable person might wonder whether the September 8th quake might have triggered Tuesday’s quake.

Lesson to be learnt: Unlike most natural disasters, there’s no way to predict or forecast earthquakes. That makes preparation way more important, whether it’s through building codes or earthquake drills.